Oil compositions containing stabilized copolymer ester-type pour point depressants



Patented Oct. 28, 1952 OIL COMPOSITIONS CONTAINING STABI- LIZED COPOLYMER, ESTER-TYPE POUR POINT DEPRESSANTS John J. Giammaria, Woodbury, N. J assignor to Socony-Vacuum Oil Company, Incorporated, a corporation of New York No Drawing. Application August 31, 1951, Serial No. 244,716

9 Claims. (01. 252-334) This invention relates to lubricating 011 compositions. More particularly, the invention relates to lubricating oil compositions containing a pour point depressant of the copolymer estertype and a basic sulfonate-type detergent.

' As is well known in the lubricating art, the various characteristics of mineral lubricating oils may be enhanced by the addition thereto of relatively small amounts of various chemical agents designed to effect certain specific improvements therein. Thus, addition agents are known which have the ability to fortify the oil against oxidation, improve its detergent action, increase its load-carrying ability, improve its viscosity, depress the pour point of the oil, etc. These chemical agents are known in the art as. antioxidants, detergents, extreme pressure agents, V. I. (viscosity index) improvers and pour point depressants. p,

' As is further known, it is the practice in the art to add to mineral lubricating oils not just one additive, but combinations of additives whereby more than one characteristic of the oil is improved. The present invention is concerned with an oil containing such a combination of additives, viz., (a) a pour point depressant of the copolymer ester-type and (b) a basic sulfonate-type detergent. In the use of these two types of additives in combination in oil, it was found that the detergent exhibited a deleterious effect on the pour point depressant, at the concentrations of additives normally used, so that the latters ability to lower the pour point of the oil was substantially destroyed. For example, 0.025 weight per cent of an esterified copolymer of the character herein contemplated lowered the A. S. T. M. pour point of a base oil from +20" F. to l5 F. but, upon adding a basic sulfonate type of detergent to this blend, the A. S. T. M. pour point was raised to F. Due

. 2 process whereby copolymer ester-type pour point depressants can be stabilized for use in oil compositions containing basic sulfonate detergents and also to provide oil compositions containing such stabilized pour point depressants and detergents.

In accordance with the present invention, it has now been found that pour point depressants of the copolymer ester-type may be successfully stabilized for use with basic sulfonate detergents by reacting the pour depressant with a small amount of a primary amine. The procedure involves adding a minor amount, from about 2 to about 10. per cent by weight, generally 3 to 4. per cent, of the primary amine to the pour depressant and heating to a temperature of from about 150 C. to about 200 C. This temperature is maintained for about /2 to 2 hours. The reaction may be carried out with or without a solvent. Suitable solvents include xylene, naphtha or other high-boiling hydrocarbons. The solvent is subsequently removed by distillation. A mineral oil may also be used as a solvent for the reaction in which case it need not be removed, but the product, being thus obtained in the form of an oil concentrate, may be added directly to the lubricating'oil sought to be improved in pour point character. When a solvent is not used, it is preferred to first heat the pour depressant to about 100 C. and then add the amine in order to avoid any thickening or gelation which may otherwise. occur.

Any primary amine of the aliphatic, aromatic,

V cycloaliphatic or heterocyclic series may be used in the invention. In general, aliphatic, straightchain, primary amines having from 1 to about to the incompatibility thus exhibited by theadw 18 carbon atoms are preferred, While those having 12 to 18 carbon atoms are particularly preferred.

Typical of the amines which may be used in the invention are the following: (a) aliphatic amines, such as methylamine, ethylamine, propylamine, 'butylamine, hexylamine, octylamine, decylamine, tetradecylamine, hexadecylamine and octadecylamine; (b) cycloaliphatic amines,

' such as cyclohexylamine and cyclopropylamine;

(0)" aromatic amines, suchas aniline, naphthylamine, toluidine and anisidine; and (d) heterocyclicamines, such as Z-aminopyridine, 2-aminothiophene and 2-aminofuran.

.-- The. copolymer ester-type pour depressants particularly contemplated herein are those prepared by copolymerizing maleic anhydride with styrene and then esterifying the copolymer product with a primary, normal, aliphatic alcohol having from 12 to 14 carbon atoms, or a mixture of alcohols having from 10 to 18 carbon atoms and an average of 12 to 14 carbon atoms per molecule. The copolymers are prepared by reacting maleic anhydride and styrene in approximately equimolar quantities in the presence of a peroxide polymerization catalyst, such as benzoyl peroxide, at a temperature of from about 50 C. to about 150 C. An excess of styrene may be used in order to insure complete reaction of the maleic anhydride, the excess styrene being conveniently removed from the reaction mixture by distillation after the reaction is complete. The reaction is generally complete in from about 1 to about 5 hours. This reaction may be conducted in a suitable solvent, such as xylene, toluene, dioxane, or the like.

The esters of the copolymers are readily prepared by reacting the copolymer and a suitable alcohol under ordinary esterification conditions. For example, the reactants may be heated at xylene reflux temperature in the presence ofcon-' centrated sulfuric acid, or p-toluene sulfonic acid, as a catalyst. As aforesaid,suitable alcohols for this purpose are the primary, normal, saturated, m-onohydric, aliphatic alcohols of from 12 to 14 carbon atoms, such as lauryl alcohol or tetradecyl alcohol, or 'a mixture of alcohols having from about to about 18 carbon atoms and an average of 12 to 14 carbon atoms per molecule. Typical of suitable alcohol mixtures are two mixtures of alcohols manufactured and marketed by E. I. du Pont de Nemours Company under the trade-names Lorol-5" and Lorol-B. These mixtures contain normal, aliphatic, saturated, monohydric aliphatic alcohols containing 10 to 18 carbon atoms in approximately the following proportions:

Although the esters prepared from maleic anhydride-styrene copolymers are particularly contemplated herein, the invention may be applied to various other copolymer ester-type pour depressants, such as the esters of other vinyl or allyl compounds copolymerized with maleic anhydride. For" example, the invention is applicable where the pour point depressant is a l-olefinmaleic anhydride copolymer ester, a vinyl-estermaleic anhydride copolymer ester, 9, vinyl-ethermaleic anhydride copolymer ester, or the like. Ester-type copolymers to which the invention is applicable are described in detail in copending applications, Serial No. 744,802, Serial No. 756,316 and Serial No. 77,288 of the present inventor, and Serial No. 736,106, now Patent No. 2,570,846 issued October 9, 1951 and Serial No. 739,652 of Ferdinand P. Otto et al.

The basic sulfonate detergents contemplated herein are particularly those obtained from aromatic hydrocarbons, substituted aromatic hydrocarbons 0r aromatic petroleum fractions and a sulfonating agent, suchas strong sulfuric acid,

oleum, chlorsulfonic acid and the like, the petro leum-type sulfonates being particularly preferred. Synthetic types of sulfonates may also be used, such as the basic metal salts of sulfo-nic acids or wax-substituted benzene and naphthalene, wherein the wax substituent is a long-chain aliphatic hydrocarbon obtained from petroleum and having at least about 18 carbon atoms and generally an average of about 24 carbon atoms per molecule.

The basic salts particularly contemplated herein: are those of the metals calcium, barium, strontium and magnesium. The basic salt is produced by: reacting the sulfonic acid with an excess of the metal hydroxide over that which would be required to neutralize it or any occluded sulfuric acid which might be present therein.

The following examples and tests will serve to illustrate the utility of the present invention.

EXAMPLE A Basic barium petroleum sulfonate A basic sulfonate detergent was prepared as follows: A Mid-Continent-type residual oil was sulfonated by slowly adding 300 parts of 103 per cent H2804 to 1000 parts of oil at loo- F. Sixty parts of H20 were added and the temperature was maintained at USO- F. for 24 hours. The upper sour oil layer was drawn off and air blown to remove dissolved-S02.

Ninety-two parts of BaO were slaked with 270 parts of water in a separate reactor. At 170 F., 1040 parts of sour oil were added. The temperature was slowly raised to 200 F. and the product was dehydrated by air blowing at this temperature. The final product was obtained by filtering under pressure at 200 F.

EXAMPLE I Mixed alcohol ester of styrene-maleic anhydride copolymer (a) A copolymer ester-type pour depressant was prepared as follows:

Sixty parts of styrene and 40 parts of maleic anhydride were dissolved in 1000 parts 0. 5 toluene by heating to 75 C. One part of benzoyl peroxide was added and the temperature was raised to 95 C. where the copolymerization reaction started. The styrene-maleic anhydride copolymer precipitated as the reaction progressed. The mixture was heated at reflux for about hour. It was then cooled to 100 C. and 177.2 parts of a mixture comprising 75 per cent by weight of Lorol-5 and 25 per cent by weight of octadecanol-l were added. One and one-half parts of concentrated H2804 were added and the mixture heated at reflux for 1 hour. The water formed during the esterification of the copolymer was collected in a Dean-Stark moisture trap. The solvent was gradually distilled from the reaction mixture and the temperature was finally raised to C. to complete the esterifica'tion.

(b) The copolymer ester from (a) was diluted with suincient mineral oil to make a 40 per cent (by weight) blend of the copolymer ester to facilitate handling. Two parts of n-dodecylamine were added to 50 parts of the oil solution of the pour depressant at room temperature. The solution became quite viscous whereupon 50 parts of xylene were added as a diluent. The temperature was gradually raised to 175 C. and the xylene removed by distillation. Heating was continued at 175 C. for 1 hour. 0n cooling to room temperature, the product remained flui-d'and showed no signs of gelling on subsequent storage.

EXAMPLE II Two parts of n-octadecylamine were added to 50 parts of the copolymer ester described in Example 1(a) and the mixture was heated at 175 C. for 1 hour.

EXAMPLE III Two parts of cyclohexylamine were added to 50 parts of the copolymer ester described inExample 1(a) at 100 C. Heating was continued to 175 C. and maintained for 1 hour.

EXAMPLE IV Two parts of aniline were added to 50 parts of the copolymer ester described in Example 1(a) at 100 C. The temperature was then raisedto 175 C. and held for 1 hour. The mixture was finally heated to 185 C. under reduced pressure toremove unreacted aniline.

EXAMPLE V This example was the same as Example 1(d) but n-butylamine was substituted for n-dodecylamine. v

Stabilization of pour point depressant f The test results shown in Table I illustrate the improvement in pour point lowering efiect obtained with the amine-modified pour depressant when used in conjunction with'a basicsulfonate detergent similar to that described in Example A, namely, a basic barium salt of a petroleum sulfonic acid. The test oil was a solventrefined, Mid-Continent type base oil having a kinematic viscosity of 6.37 centistokes at 210 and an A. S. T. M. pour point of F. It is seen from these data that the effectiveness of the untreated copolymer ester is greatly reduced when the basic detergent is added to the blend while the amine-modified products remain substantially unchanged in their effectiveness in the presence of the detergent.

The amounts of stabilized, esterified copolymer pour depressant to be used in the oil compositions contemplated herein, along with the basic sul fonate detergent, range from about 0.01 weight per cent to about 0.5 weight per cent and particularly from 0.025 weight per cent to 0.05 weight per cent. The basic sulfonate detergent, on the other hand, may be added to the oil in amounts ranging from about 1 to about 10 per cent' by weight and preferably from about 2 to 3 percent.

Other addition agents may also be used in-the oil along with the additives herein contemplated. The additive combinations herein disclosed may be prepared in the form of oil concentrates, if

desired, to provide an additive base which is readily soluble in lubricating oils.-

Although the principle of the inventionhas been illustrated by means of a particular stabilizedcopolymer ester and a specific basic sulfonate detergent, it i's-intended that theinvea tlon not be limited in any way thereby, but only as defined in the appended claims. a "What is claimed is:

1. A mineral lubricating oil containing (a) a minor amount, sufficie'nt to improve the detergent character of said oil, of a basic metal sulfonate and (b) a minor amount, sufficient to depress the pour point of said oil of an esterified 'copolymerwhich has been stabilized against the deleterious effect normally exerted on said'esterified copolymer by the basic metal sulfonate in the -oil-,-which effect reduces the ability of said esterified copolymer to lower the pourpoint of said oil; said esterified copolymer havingbeen formed by reacting a vinyl compound, selected froin'the group consisting of styrene, l-olefins, vinyl esters andvinyl ethers, with maleic anhydride -inabout equimolarquantities and then esterifying the copolymer thus formed withan alcohol material selected from the group consisting ofprimary, normal, saturated, aliphatic alcoholsliaving from! 12 to 14 carbon atoms and a *mixture of. primary, normal, saturated aliphatic alcohols having-from 10 to 18 carbon atoms and an average of from-.12 to 14 carbon atoms per molecule; :said esterified copolymer having been stabilized by reaction of said vesterified copolymer with from about 1 to about 10 per cent by weight ofa primary amineaat a temperature of from about C. toabout 200 0., for a period of from about 1 to about 5 hours.

2. Amineral lubricating oil containing (a) a minor amount, sufficient to improve the detergent character of said oil, of abasic metal sul- -.fonate and (.b) a minor amount, sufiicient to depress the pour pointof said oil of an esterified copolymer which has been stabilized against the deleteriousefiect normally exerted on said ester- ,ified copolymer by the basic metal sulfonate in atheoiLwhich effect reduces the ability of said esterified copolymer. to lower the pour point of .Said o i1;said esterifie'd copolymer having been iormed by reacting styrene with maleic anhydride about equimolar quantities and then estmjfifing theacopolymer thus formed with an alcohol material selected from the group consisting of primary, normal, saturated, aliphatic alcohols having from 12 to 14 carbon atoms and a mixture of primary, normal, saturated aliphatic alcohols having from'lo to 18 carbon atoms and .an average offromi 12 to 14 carbon atoms per molecule; said'esterified copolymer having been stabilized by reaction of said esterified copolymer withlfrom about 1 to about 10 per cent by weight ,of a primary amine at a temperature of from about .125" C. to about 200 C., for a period of from about'l to about 5 hours.

3. A mineral lubricating oil containing (a) a minor amount, sufizlcient to improve the detergent character of said oil, of a basic metal petroleum 'sulfonate and (D) a minor amount, sufficientto depress the hour point or said oil of an esterified copolymer which has been stabilized against the deleterious efiect normally exerted on said esterified copol'ymer by the basic metal petroleum sulfonate in'thejdil, which effect reduces the ability of said esterified copolymer to lower the pour point of said oil; said esterified copolyrner having been formed byreacting styrene with maleie anhydride" in' about 'equimolar quantities and then esterifyingthe copolymer thus formed with an alcohol material. selected from the group con- 'sisting'of primary, normal, saturated, aliphatic alcohols having from 12,to..14 carbon atoms and a mixture of primary, normal, saturated, aliphatic alcohols having from 10 to 1-8 carbon atoms and an average of from 12 to 14 carbon atoms per molecule; said esterified copolymer having been stabilized by reaction of said esterified copolymer with from about 1 to' about 10 per cent by weight of a primary amine at a temperature or from about 125 C. to about 200 C., ,for a period of from about 1 to about 5 hours.

4. A mineral lubricating oil containing (a) a minor amount, sufficient to improve the detergent character of said oil, of a basic barium petroleum sulfonate and (b) a minor amount, sufficient to depress the pour point of said oil of an esterified copolymer which has been stabilize against the deleterious effect normally exerted on said estcrified copolymer by said basic barium petroleum sulfonate in the oil, which reflect reduces the ability of said esterified copolymerto lower the pour point of said oil; said esterified co olymer having been formed by reacting styrene with maleic anhydride in about equimolar quantities and then esterifying' the copolymer thus formed with an alcohol material selected from 'thegroup consisting of primary, normal, saturated, aliphatic alcohols having from 12 to 14 carbon atoms and a mixture of primary, normal, saturated aliphatic alcohols having from 10 to 18 carbon atoms and an average of from 12 to 14 carbon atoms per molecule; said esterified copolymer having been stabilized by reactionQof said esterified copolymer with from about 1 to about .10 per cent by weight of a primary amine at a temperature of from about 125 C. to about 200 C., .for a period of from about 1 to about 5 hours.

5. A mineral lubricating oil containing (a) a minor amount, sumcient to improve the detergent character of said oil,-'of a basic barium petroleum sulfonate and (b) a minor amount, suiiioient to depress the pour point-of said oil of an esterified copolymer which has been stabilized against the deleterious efiect normally exerted on said esterified copolymer by the basic barium petroleum sulfonate in the oii,'ywhich efiect reduces the ability of said esterified copolymer to lower the r pour point of said oil; said esterified copolymer having been formed by reactingstyrene with maleic anhydride in about equimolar quantities and then esterifying the copolymer thus formed with a mixture of primary, normal, saturated,

aliphatic alcohols having from 10 to '18 carbon atoms and an average of from 12 to '14 carbon atoms per molecule; said esterified copolymer having been stabilized by reaction .ofsaid asterified copolymer with from about 1 to about :10

copolymer which has been :stabilized against the deleterious efiect normally exerted on said esterifled copolymer by said basic barium petroleum sulfonate in the oil, whichefieot reduces the ability of said esterified copolymer to lower the pour point of said oil; said esterified copolymer having been formed by reacting styrene with maleic anhydride in about equimolar quantities and then esterifying the copolymer thus formed with .a mixture of primary, normal, saturated (aliphatic alcohols having from in to 1.8 carbonatoms and an average of from 12 to 14 carbon atoms per molecule; said esterified copolymer having beenstabilized by reaction of said esterifled copolymer with from about 1 to about 10 per cent by weight of n-butylamine at a temperature of from about 125 C. to about 200 C., for a period of from about 1 to about 5 hours.

7. A mineral lubricating oil containing (a) a minor amount, sufficient to improve the detergent character of said oil, of a basic barium petroleum sulfonate and (b) a minor amount, suincient to depress the pour point of said oil of an esterified copolymer which has been stabilized against the deleterious efiect normally exerted on said esterified copolymer by said basic barium petroleum sulfonatein the oil, which efiect reduces the ability of said esterified copolymer to lower the pour point of said oil; said esterified copolymer having been formed by reacting styrene with maleic anhydride in about equimolar quantities and then esterifying the copolymer thus formed with a mixture of primary, normal, saturated aliphatic alcohols having from 10 to 18 carbon atoms and an average of from 12 to 14 carbon atoms per molecule; said esterified copolymer having been stabilized by reaction of said esterified copolymer with from about 1 to about 10 per cent by weight of n-hexadecylamine at a temperature of from about 125 C. to about 200 (3., for aperiod of from about 1 to about 5 hours.

8. A mineral lubricating oil containing (a) a minor amount, sufiicient to improve the detergent character of said oil, of a basic barium petroleum'sulfonate and (b) a minor amount, sufficient to depress the pour point of said oil of an esterified copolymer, stabilized against the deleterious'efiect normally exerted on said esterifled copolymer by said basic barium petroleum sulfonate in the oil, which effect reduces the ability of said esterified copolymer to lower the pour point of said oil; said esterified copolymer having been formed by reacting styrene with maleic anhydride in about equimolar quantities and then esterifying the copolymer thus formed with a mixture of primary, normal, saturated aliphatic-alcohols having from 10 to 18 carbon atoms and an average of from 12 to 14 carbon atoms per molecule; said esterified copolymer having been stabilized by reaction of said esterifled copolymer with from about 1 to about 10 per cent by weight of cyclohexylamine at a temperature of from about 125 C. to about 200 0,, for a period of from about 1 to about 5 hours.

9. A mineral lubricating oil containing (a) a minor amount, suflicient to improve the detergent character of said oil, of a basic barium petroleum sulfonate and (b) a minor amount, sufficient to depress the pour point of said oil of anesterified copolymer which has been stabilized against the deleterious efiect normally exertedon said esterified copolymer by said basic barium petroleum sulfonate in the oil, which effect reduces the ability of said esterified copolymer to lower the pour point of said oil; said esterified copolymer having been formed by reacting styrene with maleic anhydride in about equimolar quantities and then esterifying the copolymer thus formed with a mixture of primary. normal, saturated aliphatic alcohols having from 10 to 18 carbon atoms and an average of from 12 to 14 carbon atoms per molecule; said esterified copolymer having been stabilized byreaction of said esterified copolymer with from about v1. :to about 10 per cent by weight of aniline ratatemperature of irom about125 C. to about 200 C., for a. period of from about 1 to about 5 hours.

JOHN J. GIAMMARIA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Voss et a1. July 14, 1936 Nuesslein et a1 Aug. 8, 1939 Number 10 Name Date Perrin et a1 May 14, 1940 Arnold et a1 Nov. 10, 1942 Frolich et a1 Aug. 24, 1943 Blair Feb. 22, 1944 Gleason Jan. 2, 1945 Dietrich Mar. 6, 1945, Blair May 8, 1945 Hanford June 19, 1945 Woodward Mar. 26, 1946 Rust Aug. 2, 1949 

1. A MINERAL LUBRICATING OIL CONTAINING (A) A MINOR AMOUNT, SUFFICIENT TO IMPROVE THE DETERGENT CHARACTER OF SAID OIL, OF A BASIC METAL SULFONATE AND (B) A MINOR AMOUNT, SUFFICIENT TO DEPRESS THE POUR POINT OF SAID OIL OF AN ESTERIFIED COPOLYMER WHICH HAS BEEN STABILIZED AGAINST THE DELETERIOUS EFFECT NORMALLY EXERTED ON SAID ESTERIFIED COPOLYMER BY THE BASIC METAL SULFONATE IN THE OIL, WHICH EFFECT REDUCES THE ABILITY OF SAID ESTERIFIED COPOLYMER TO LOWER THE POUR POINT OF SAID OIL; SAID ESTERIFIED COPOLYMER HAVING BEEN FORMED BY REACTING A VINYL COMPOUND, SELECTED FROM THE GROUP CONSISTING OF STYRENE, 1-OLEFINS, VINYL ESTERS AND VINYL ETHERS, WITH MALEIC ANHYDRIDE IN ABOUT EQUIMOLAR QUANTITIES AND THEN ESTERIFYING THE COPOLYMER THUS FORMED WITH AN ALCOHOL MATERIAL SELECTED FROM THE GROUP CONSISTING OF PRIMARY, NORMAL, SATURATED, ALIPHATIC ALCOHOLS HAVING FROM 12 TO 14 CARBON ATOMS AND A MIXTURE OF PRIMARY, NORMAL, SATURATED ALIPHATIC ALCOHOLS HAVING FROM 10 TO 18 CARBON ATOMS AND AN AVERAGE OF FROM 12 TO 14 CARBON ATOMS PER MOLECULE; SAID ESTERIFIED COPOLYMER HAVING BEEN STABILIZED BY REACTION OF SAID ESTERIFIED COPOLYMER WITH FROM ABOUT 1 TO ABOUT 10 PER CENT BY WEIGHT OF A PRIMARY AMINE AT A TEMPERATURE OF FROM ABOUT 125* C. TO ABOUT 200* C., FOR A PERIOD OF FROM ABOUT 1 TO ABOUT 5 HOURS. 